1. Field of the Invention
The present invention relates to a method for manufacturing laminated material coated with thermoplastic resin and an apparatus for manufacturing such laminated material, and more particularly, to a method for manufacturing laminated material which is used as material for can, material for construction, material for automobile interior, material for electric appliances, material for furniture and the like and an apparatus for manufacturing such laminated material.
2. Description of the Related Art
Conventionally, to enable a metal sheet which constitutes a substrate to have the corrosion resistance, a laminated material which is formed by laminating a resin film to a metal sheet has been widely known.
As a method for manufacturing such laminated material, a method which coats a material which is produced by dispersing epoxy resin-based thermosetting resin, phenol resin-based thermosetting resin, acrylic resin-based thermosetting resin, polyester resin-based thermosetting resin into a solvent to a surface of the substrate, a method which laminates a preformed film such as a polyester-based film, an olefin resin-based film, a polyamide-based film to a substrate using an isocyanate-based adhesive agent, an epoxy-based adhesive agent or a phenol-based adhesive agent, and the like have been known.
Further, there has been also known a method in which a substrate and thermoplastic resin are laminated by making use of the heat adhesion ability of the thermoplastic resin. As such a method, there has been known a method which adheres a preformed film made of thermoplastic polyester to a metal sheet by heat or a method which adheres a resin film made of extruded thermoplastic polyester resin to a substrate by heat.
Among these methods, as the method which adheres the resin film made of the extruded thermoplastic resin to the substrate by heat, following techniques have been disclosed.
For example, in International Patent Publication 503378/1999, a method which coats resin on both surfaces of a metal strip while extruding the resin and forming films is disclosed. In the method, the metal strip made of aluminum alloy, for example, is moved through a provisional conditioner, two sets of extruding dies, a post heating machine and a cooling system thus coating the both surfaces of the strip with thin polyester material coatings. In an apparatus shown in FIG. 1 of the specification of this publication, thin films made of polyester which are extruded from the dies are stretched to be made thin by first rolls (stretching rolls), are cooled by second rolls (rolling contact rolls) and are adhered to the heated metal strip under pressure using third rolls (lamination rolls).
Further, Japanese Laid-open Patent Publication 138315/1998 discloses a method for manufacturing resin/metal laminated material. In such a method which forms a resin coating or film on at least one of surfaces of a metal substrate, along a path of the metal substrate, a region in which the metal substrate is heated, a die which supplies thermoplastic resin in a film form, a pair of hot lamination rolls which make the thermoplastic resin adhered to at least one of surfaces of the metal substrate and quenching means for quenching the formed laminated material are arranged. Further, the resin film made of thermoplastic resin which is supplied from the die is supported and transported by warm laminate rolls corresponding to the resin film so that the resin film is supplied to a nip position between the warm laminate rolls whereby the thin film made of thermoplastic resin is adhered by melting to at least one of surfaces of the heated metal substrate by the warm laminate rolls.
Further, Japanese Laid-open Patent Publication 80935/1995 and Japanese Laid-open Patent Publication 80936/1995 and the like propose a following method as a method which manufactures a laminated metal sheet by coating resin films extruded from T-dies to the metal sheet. That is, in the manufacturing method of the laminated metal sheet, at the time of allowing molten thermoplastic resin to be pressed by a pair of rolls and to flow down to an interface of one surface of the metal sheet and one of a pair of rolls from the T-die, the metal sheet is preheated such that the preheated temperature of a center portion of the metal sheet is set higher than the preheated temperature of end portions of the metal sheet and, thereafter, the molten thermoplastic resin is allowed to flow such that the thermoplastic resin is coated and adhered to one surface of the metal sheet temporarily, and the end portions of the formed thermoplastic resin film are removed, and then at least end portions of the obtained thermoplastic resin-coated metal sheet is heated again.
However, when the resin film is extruded from the T-die using such a method, both end portions (ear portions) of the resin film are contracted in the course of solidification by cooling so that a so-called neck-in phenomenon which makes both end portions of the resin film thick tends to occur whereby a laminating film obtained after solidification by cooling becomes a laminating film whose thickness at both end portions (ear portions) in the widthwise direction become thicker than the thickness at other portions. When the laminating film which has such thick ear portions is directly laminated to the substrate, a laminated material which has the substrate coated with the laminating film having different thickness in the widthwise direction is formed. Accordingly, usually, after solidification by cooling, the ear portions are cut (trimmed) by approximately 30 to 50 mm and, thereafter, the laminated material is wound by a winding machine. Then, the laminating film having the uniform thickness and the substrate are laminated.
Further, in the method disclosed in the above-mentioned Japanese Laid-open Patent Publication 80935/1995, Japanese Laid-open Patent Publication 80936/1995 and the like, it is necessary to cut and remove the ear portions together with the substrate after the lamination and the trimmed ear portions constitute composite materials made of the ear portions and the substrate so that this also gives rise to a problem with respect to the disposal of scraps.
Further, in the manufacturing of the laminated material which is used as can material, the can forming requires a strong working so that there also arises a technical problem that a thin laminating film must be firmly adhered to the substrate such as a metal sheet while ensuring the uniform thickness.
The present invention has been made in view of the above-mentioned problems of the related art and it is an object of the present invention to provide a method for manufacturing laminated material which can remove ear portions of a resin film extruded from an extruding machine, can directly laminate the resin film to the substrate and can also make the disposal of end portions of the laminated material after lamination unnecessary and to provide a manufacturing apparatus which can be used in such a manufacturing method.
It is still another object of the present invention to provide a method for manufacturing resin laminated material which can prevent the softening of metal by heating and the thermal modification and thermal oxidation of resin as much as possible and exhibits the remarkably excellent adhesiveness of the resin film to a substrate while ensuring a uniform laminating film thickness with high productivity and high product yields.
It is a further object of the present invention to provide a method for manufacturing laminated material in which the formed laminated material can withstand the working of large degree such as deep drawing working, bending and stretching working and ironing working and the formed body after working exhibits the excellent corrosion resistance whereby it is possible to provide a method for manufacturing laminated material useful for application to can material.
A method for manufacturing laminated material according to the present invention which laminates a resin film formed by extruding molten thermoplastic resin from a T-die to a substrate is characterized in that a laminating film is formed by cutting ear portions (lug portions) of the resin film before lamination and the laminating film is laminated to the substrate.
Further, a method for manufacturing laminated material according to the present invention which laminates a resin film formed by extruding molten thermoplastic resin from a T-die to a substrate is characterized in that the resin film is temporarily received and held by a pre-roll, then ear portions of the resin film are cut before lamination to form a laminating film, and the laminating film is laminated to the substrate.
Further, a method for manufacturing laminated material according to the present invention which laminates a resin film formed by extruding molten thermoplastic resin from a T-die to a substrate is characterized in that ear portions of the resin film are cut and a flattened portion is cut to form a plurality of strips made of laminating films before lamination, and a plurality of strips made of laminating films are laminated to the substrate.
In these methods for manufacturing laminated material, the thermoplastic resin is made of polyester and a temperature of the resin film at the time of cutting is preferably set to equal to or more than the glass transfer point (Tg).
An apparatus for manufacturing laminated material according to the present invention includes heating means which preheats a substrate, a T-die which extrudes molten thermoplastic resin as a resin film, cutting means which forms a laminating film by cutting ear portions of the resin film before lamination, lamination rolls which laminate the laminating film to the substrate, and a cooling device which quenches the formed laminated material.
Further, an apparatus for manufacturing laminated material according to the present invention includes heating means which preheats a substrate, a T-die which extrudes molten thermoplastic resin as a resin film, a pre-roll which temporarily receives the resin film which is extruded from the T-die, cutting means which forms a laminating film by cutting ear portions of the resin film before lamination, lamination roll which laminate the laminating film to the substrate, and a cooling device which quenches the formed laminated material.
Still further, an apparatus for manufacturing laminated material according to the present invention includes heating means which preheats a substrate, a T-die which extrudes molten thermoplastic resin as a resin film, cutting means which forms a plurality of strips of laminating films by cutting ear portions of the resin film and also by cutting flattened portion before lamination, lamination rolls which laminate a plurality of strips of laminating films to the substrate, and a cooling device which quenches the formed laminated material.
In these apparatuses for manufacturing the laminated material, the lamination roll is preferably formed of a lamination roll having stepped portions.
In these apparatuses for manufacturing the laminated material, the cutting means is preferably formed of laser beams.
In these apparatuses for manufacturing the laminated material, a laser beam device is disposed above the lamination rolls.
In these apparatuses for manufacturing the laminated material, a pair of T-dies and cutting means are arranged in substantially symmetry with respect to a surface of the substrate and the laminating films are laminated to both surfaces of the substrate.